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basin as well as the timing of the dam failures and how the contribution of those discharges may <br />have added to the peak discharge at that location. In order to answer questions brought by the <br />residents of the community around the X Bar 7 Ranch, the contributions of the main stem, West <br />Fork and Meadow Lake needed to be combined with those from the North Fork of the Little <br />Thompson River joining from the north and Rowell Gulch joining from the south. <br />Subbasin delineation was judged to be more critical in the BEMA area in order to more accurately <br />portray the timing and duration of dam overtopping. As a result, five subbasins representing the <br />contributing drainage areas for each dam were delineated within the larger basin and labeled with <br />as the respective dam name. Figure 18 shows delineation of the subbasins created for the Big Elk <br />Meadows Dams. <br />> <br />COLORADO <br />anwr! ae we uv a[unea! <br />�� Dlvfsian of Waxer Rc3aurces ��na"r."aars <br />i��iZZ3�ii Pw railuRGS i.nsicniirn, 1 <br />U.A 50M BRANCH <br />Figure 18 - Map of Big Elk Meadows Dams subbasin delineation for rainfall- runoff modeling. <br />10.6 Rainfall Temporal Distribution Analysis <br />A key part of this investigation was to attempt to accurately portray the spatial distribution, or <br />area of rainfall and the temporal distribution, or how the rain fell through time during the event. <br />As previously described, the Dam Safety Branch contracted with Applied Weather Associates, LLC <br />to obtain 5- minute incremental subbasin average rainfall from 1:05 am MDT on September 8 to <br />1:00 am MDT on September 18, 2013 to capture the full extent of the storm. The spatial extent <br />and total depths of the rainfall derived from their analysis is shown above in Figure 8. The <br />temporal distribution of the rainfall within each subbasin is shown below in Figure 19. The basin - <br />averaged rainfall data were input as Precipitation Gage elements for each subbasin in the HEC- <br />HMS model. The tabulated rainfall data from which the basin averages were calculated are <br />presented in Appendix C. <br />Report of the September 2013 Little Thompson River Flooding COLORADO <br />and Big Elk Meadows Dam Failures, June 2014 (Revised, Dec 2014) a Division of Water Resources <br />Page 21 of 48 Department or r.alul,r 4„50 rc <br />DAM SAFETY BRANCH <br />